Out attitude toward ourselves at first is learned from how other's respond to us. Sounds like someone else told you you weren't good enough for them and instead of questioning it you went along with their program. Who are you competing against that you have to be better? You cannot ever beat yourself, you are yourself! If you want something you try for it and get it, but whether you barely get it or get it over the top. . . getting it is the goal and no one really cares how (unless it is illegal :-) Once you are in college, your high school grades don't matter; once you graduate from college your college grades don't matter; once you make your first million, you're just working on your second million

I'm taking a class right now and not getting the grades I expected but I realized that I am learning what I wanted to learn and I like my papers, even if my tutor does not, etc. Don't forget that Einstein flunked high school math; his teacher had no clue. You are the right size, it is the pants that don't fit. You should be working for and enjoying yourself, not beating yourself up because of some presumed exterior standard you don't meet.